This Program Project grant focuses on understanding the basic mechanisms that underlie diabetic gastroparesis and immediately translating those findings into new therapeutic solutions for our patients. This is important, as current therapeutic approaches for our patients with diabetic gastroparesis are largely ineffective. This highly productive Program Project is organized around 3 projects and 3 cores resulting in a tightly integrated Program Project. We will accomplish the overall objective of the Program Project by taking advantage of the cutting edge discovery work in all three Projects and making these discoveries immediately clinically relevant in Project 3. Project 1 utilizes a wide variety of innovative tools including next generation sequencing to determine the common unifying abnormality that leads to the diverse cellular changes seen in diabetic gastroparesis. Preliminary data suggest that macrophages are key to the development of diabetic gastroparesis and that modulation of macrophage subtypes and the heme oxygenase 1 pathway can reverse cellular injury and normalize gastric function. Project 2 will utilize state of the art tools to focus on the epigenetic control of neuronal nitric oxide synthase (Nos1, nNOS). Tissue-level reduction in Nos1 expression was the first specific form of diabetic enteric neuropathy described. Project 2 will examine a transcriptional/epigenetic network consisting of bone morphogenetic protein (Bmp)-Smad-Ep300/Crebbp histone acetyltransferases (HATs), hypoxia-inducible factor 1a (Hif1a)-Ep300/Crebbp HATs and insulin/insulin-like growth factor 1 (Igf1)-Ezh2 histone methyltransferase and proposes that this network regulates the pool of Nos1-expressing neurons in health and diabetic gastroparesis. Project 3 will continue to focus on understanding the mechanisms responsible for gastric emptying disturbances in diabetes and on developing highly novel management approaches for this condition including clinical trials. The Projects are supported by equally cutting edge cores. Core A will provide administrative support. Core B will support the epigenomic and transcriptomic experiments carried out by all three Projects by providing ChIP-seq, RNA-seq and DNA methylation expertise and tertiary bioinformatics analysis. Core C as a Physiological Characterization and Data Integration Core will provide service for all three Projects by performing gastric emptying and blood glucose assays in mice and mucosal ion flux in human biopsies, maintaining an Electronic Animal Research Record and developing and maintaining a platform for the integration of data collected in the Program Project. Together this highly integrated, synergistic and collaborative Program Project will mechanistically determine the underlying pathobiology of diabetic gastroparesis and use this information to devise and test therapies in patients in a very short bedside to patient time frame.